FIELD: oil and gas industry.
SUBSTANCE: invention is related to method for liquefaction of nitrogen-containing input fraction enriched with hydrocarbons, preferably natural gas. The method includes the following stages: a) the feed fraction (1) is burned (E1, E2); b) divided by fractional distillation (T1) to the fraction enriched with nitrogen (9), wherein methane content is max. 1 vol. %, and the nitrogen-depleted fraction enriched with hydrocarbons (4); c) the above fraction (4) is overcooled (E3) and expanded (b); d) the expanded nitrogen-depleted fraction enriched with hydrocarbons (5) is divided (D1) into liquid fraction enriched with nitrogen (6), wherein nitrogen content is max. 1 vol. %, and fraction enriched with nitrogen (7); and e) the fraction enriched with nitrogen (7) is added to the feed fraction (1).
EFFECT: method allows removal of all nitrogen contained in the feed fraction either by liquid product gas or by highly-concentrated nitrogen fraction.
7 cl, 2 dwg
